Thermometric method and apparatus for determining the amount of impregnite in cloth



March 16, 1 w. c. JOHNSON ET AL:

THERMOMETRIC METHOD AND APPARATUS FOR DETERMINING THE AMOUNT OF IMPREGNITE IN CLOTH Filed May 22, 1945 WLCMW Patented Mar. 16, 1954 THERMOMETRIC METHOD AND APPARATUS FOR DETERMINING THE AM OUNT- OF IM- PREGNITE IN CLOTH WarrenC. Johnson'andPhilip Wehner, Chicago,

Ill., assignors to the-UnitedStates 'of' America as represented by theSecretaryof th'e Navy- ApplicationMayZZ, 1945, Serial No. 595,144

4 Claims. (Cl. 23230)" This inventionrelates to a method of. and apparatus for determining the amount of impregnitein. impregnated cloth. This method is based upon a determination of the heat or other effects produced when the impregnated cloth comes in contact with a reducing agent.-

This method-has been developed to provide a practical and rapid evaluation, for shipboard and field use, .of the protective capacity of impregnated clothing against vesicants. It is not intended to serve as a means for thequantitative determination of the amount of impregnite in cloth, but to provide a very satisfactory indication of whether a given cloth contains no impregnite, a moderate amount, or is fully impregnated. In other words, itis to be used for determining whether impregnated cloths ofifer' no protection, moderate protection, or full protection against vesicants;

The term impregnite includes-those compounds which are capable of reacting with vesicants and rendering them non-vesicant. In general, the term includes water-insoluble oxidizing agents containing nitrogen and chlorine in N--CL groups, such as chloramides and-chloroureas.

In thereaction of impregnite with vesicants, the vesicants act as reducing agents, and 7 iii for the purposeofdeterminingthe amount of impregnite in impregnatedcloth, either the vesi cants themselves or other-reducing agents which-.

react in a similar mannermay be utilized. These other reducing agents may be termed simulants or mustard simulants, and include such-compounds as phenylhydrazine, hydrogen. sulfide,

thioxane '(lA-oxthiane), dithiane .(1,4-diethyl.-.,-

enedisulfide), aniline, triethylamine, and. piperidine.

The determination is based upon thefa-ct that an approximately linear relationship exists intheamount of heat or other efi'ects liberated in' the reaction between an impregnite and av reducing agent. When a certain amount of a chemical reI- agent, suchuas phenylhydrazine, is applied to. a

prescribed area of fabric, say one inchl'in diam-- eter, containing.-impregnite,..there' is. a reaction 1 which evolves heat or other eiie'cts. 'lh'greaterl the content of impregnite in a given quantityof cloth the greater the amount of heat or other efiects evolved.

The determination of the amountwof heat galvanometer movement. The galvanometer deflectionis approximately proportional to the amount of impregnitein the'cloth. It is necessary to calibrate the 'galvanometer movement with an identical cloth containing known amounts" of impregnite. It'appears that the heat effect is independent of the type of impregnite contained in the cloth. The accuracy of the determination by this method is found to be within 10 to 15 percent of the impregnite content determined by direct quantitative analysis.

It is evident that in order to obtain the maximum heat efiect from a given area of cloth containing the impregnite, it is essential to overwhelm the impregnite with'a reducing agent, so to speak, in order to obtain the heat of the reaction in as shorta period of time as possible. This can be done by using a liquid reducing agent, or a solution of a solid reducing agent, which will penetrate the cloth and cause immediate reaction with the impregnite. Such a reducing agent, however, should not be too volatile, since a cooling effect would then be obtained due to the heat of evaporation.

The measurements are accomplished by means of an apparatus designed for use with a specified amount of a reagent on a definite area of cloth, separated by a fixed distance from a thermopile.

The principal object of this invention is to provide a method of determining the amount of impregnite in cloth by applying phenylhydrazine to an impregnated cloth and associating the heat liberated therefrom with a thermopile.

Anotherobject of this invention is to provide a method of determining the amount of impregnite by subjecting impregnated materials to the infiuence of areducing agent and associating the ei fects thereof with indicating means.

A still further object of this invention is to provide an instrument for measuring the amount of impregnite in cloth.

The invention will now be described with reference to the accompanying drawing, in which:

The figureis a half sectional drawing of the device electrically connected toa galvanometer.

Referring to the drawing, numeral l indicates a tubular glass housing in which is mounted a thermopile 2 embedded in a core 3 of plaster of paris. Said core is molded in said tube approximately /g' inch from the top end of said tube so as to provide a large lower chamber 5 and a small upper chamberdr The hot junctions 6 of said thermopile I-protrude throughthe top of plaster core 3, and thercold-junctions' L1. protrude through the bottom of said plastertcore 3, 50 thatisaid exposed thermojunctions can be freely subjected to a thermal environment. As a consequence of such mounting, the hot junctions are approximately inch from the top end of tube I. Thermopile terminals I and 8 are connected to galvanometer 9 terminals l and I l, respectively. Said galvanometer is calibrated with cloth identical to that to be tested, and containing known amounts of impregnite. Small holes l9 and HI are provided in the wall of tube to allow the passage of conductors l and I6 that connect the thermopile 2 with the galvanometer 9. Lower chamber 5 which contains the cold junctions I1 is sealed ofi with a glass plate I8.

In making an analysis, a single thickness of the cloth [2 to be tested is stretched across the upper open end of the glass tube l and held in place by a glass ring l3 which fits around the periphery of said tube. Thus the cloth is firmly held between the ring I3 and the periphery of the glass housing. After allowing about 30 seconds for the galvanometer 9 to return to the zero point and to become steady, two drops of a mustard simulant, for example, phenylhydrazine, is then placed at the center of the cloth sample within the ring. Two drops, approximately 0.1 cc., of the liquid is used in each test, but it should be stated that the amount of the liquid simulant is not particularly critical, since if only one drop is used, the deflection is found to be only 10% less, and three drops increases the deflection only slightly. After the liquid simulant has been administered, the galvanometer needle moves slowly over a period of about ten seconds to a maximum value, where it remains for a few seconds, and then slowly returns to its former position. After the maximum deflection has been read, the cloth is removed and the upper chamber 4 containing the hot junctions is allowed to stand for two to three minutes to permit diffusion of the simulant vapors out of said chamber. It is found that this amount of time is required before the galvanometer needle returns to its initial position. The total time required for carrying out such a test is about four minutes, though this may be reduced by flushing the chamber 4 with an air stream. It is necessary to allow the upper chamber 4 to become free from simulant vapors before another test is carried out, otherwise those vapors will react with a fresh piece of cloth and thereby produce erroneous results. For convenience, the zero point of the galvanometer is usually taken as a few millimeters from the extreme left-hand side of the scale. It is found necessary, after the cloth is inserted, to wait about one-half minute for the galvanometer needle to reach the selected zero point, since a heat effect is produced merely by the process of inserting the cloth into its fixed position.

In the testing of cloth, mustard vesicant either in the liquid or vapor form may be used directly, but for shipboard use or for field use it is evident that it would be more desirable to use a substance which reacts with the impregnite in a manner similar to that of mustard vesicant, but which does not have the objectionable properties which mustard vesicant possesses. In addition, the rate of the reaction between mustard vesicant and an impregnite is not as high as one would like for a rapid test.

Gas, such as hydrogen sulfide and sulfur dioxide can be used as the mustard simulant. Whereas fairly reproducible results can be obtained with the gases, they nevertheless possess several disadvantages. In the first place, the rate of thereactionfbetween thegas and the impregnite is low and in addition, the heat effects are small. Another objectionable feature is the odor and toxicity of these two gases.

A number of liquid simulants can be used, such as triethylamine, piperidine, dimethyl sulfide, thioxane, aniline, phenylhydrazine, dithiane dissolved in acetylene tetrachloride, p-phenylene diamine dissolved in acetylene tetrachloride, and solutions of these same substances in aniline.

In the case of the triethylamine, the heat effect is large, but there is also a marked cooling effect due to the rapid evaporation of the solvent. Piperidine behaves in a manner quite similar to that of triethylamine. Dimethyl sulfide is extremely unpleasant to work with, and in addition, possesses the disadvantages of triethylamine. Thioxane also has a disagreeable odor and the heat effect produced is only about half that obtained with phenylhydrazine. In the case of the solutions the heat effects are too small in each instance. Aniline appears to be about as satisfactory as phenylhydrazine; the heat effect obtained is about the same and the rate of evaporization is not too great. Of all the simulants tested, phenylhydrazine appears to be the most satisfactory.

It is understood that reducing agents can be used that liberate effects other than heat, so that responsive means such as a photo electric cell could be used in lieu of a thermopile to indicate measurements of impregnite content through means of the light effect emitted from the reaction.

It is also understood that the cooling effect of a reaction could be utilized as well as the heat effect of a reaction. In thi event, the galvanometer movement could be arranged for a swing clearance to the left instead of to the right as hereinbefore provided.

Reducing agents in the form of solids, liquids, or gases can be used with this method; however, those chemicals are preferred that have a high rate of reaction with the impregnite.

What we claim is:

1. In a method of determining the amount of impregnite in cloth, the steps of measuring a specific area of impregnated cloth, placing said area of impregnated cloth a fixed cooperative distance from the hot junctions of a thermopile connected to a galvanometer, applying a specific quantity of at least one reducing agent selected from the group consisting of phenylhydrazine and aniline to said impregnated cloth, reading said galvanometer, and calibrating said thermopile and said galvanometer with an identical cloth and area containing known amounts of impregnite and said specific quantity of said reducing agent.

2. In a method of determining the amount of impregnite in cloth, the steps of placing impregnated cloth a cooperative distance from thermal responsive means connected to a galvanometer, applying to said cloth a known quantity of a reducing agent which liberates heat in reaction with impregnite, reading said galvanometer, and calibrating said thermal responsive means and said galvanometer with an identical cloth containing a known amount of impregnite.

3. The method of measuring the amount of impregnite in cloth comprising the steps of placing impregnated cloth a cooperative distance from thermal responsive means calibrated with an identical cloth under identical conditions containing known amounts of impregnite, applying an associated known quantity of a reducing agent which liberates heat in reaction with impregnite, and measuring the amount of heat liberated, whereby the standard and unknown may be compared.

4. In a device for measuring the impregnation of cloth with impregnite, an upright container having an open upper end, a thermopile having a hot function end and acold function end, insulating means supporting said thermopile within said container with the hot function end thereof adjacent the open end of said container, :1 galvanometer connected'to said thermopile, and retaining means associated with the upper end of said container for holding impregnated cloth 6 over said open end of said container, whereby heat generated by application of a mustard simulant to said cloth produces an indication on said galvanometer.

5 WARREN C. JOHNSON.

PHILIP WEHNER.

References Cited in the file of this patent UNITED STATES PATENTS 10 Number Name Date 1,489,039 Mack Apr. 1, 1924 2,190,817 Wisfeld Feb. 20, 1940 2.477.526 Perley July 26, 1949 

3. THE METHOD OF MEASURING THE AMOUNT OF IMPREGNITE IN CLOTH COMPRISING THE STEPS OF PLACING IMPREGNATED CLOTH A COOPERATIVRE DISTANCE FROM THERMAL RESPONSIVE MEANS CALIBRATED WITH AN IDENTICAL CLOTH UNDER IDENTICAL CONDITIONS CONTAINING KNOWN AMOUNTS OF IMPREGNITE, APPLYING AN ASSOCIATED KNOWN QUANTITY OF A REDUCING AGENT 